As a production method of an optically active hydroxy compound from a carbonyl compound by asymmetric transfer hydrogenation using an iridium complex, J. Am. Chem. Soc. 2004, 126, 3020-3021 discloses a method using an iridium aqua complex represented by

In addition, Eur. J. Inorg. Chem. 2001, 1361-1369 discloses a chiral iridium aqua complex having perchlorate ion.